There are a lot of tips and tricks that you can use to optimize your email marketing. From engaging subject lines, optimal image use, captivating copy and pitch-perfect CTAs, the dedicated email marketer has no small number of ways to make sure that subscribers are fully incentivized to open, click through, and become conversions.
But what if the subscriber never gets your email in the first place?
Subscribers cannot read emails that they never get, and so your deliverability rate is crucial. It is the foundation for everything else that happens with your email marketing, and your open, click-through and conversion rates are all going to be 0% if that email never lands in the inbox in the first place.
With that in mind, it’s essential that your organization give a lot of thought to email deliverability optimization. During the course of this article, we plan on deep-diving into email deliverability best practices, tracking email deliverability, and using such automated email marketing platforms as HubSpot to improve email deliverability.
Table of Contents
Never Use Web Scraping to Obtain Email Addresses
Web scraping is the practice of using automated ‘scraping’ tools to extract useful data from a website – in this case, email addresses that you can add to a mailing list.
This is a terrible idea for email marketing, and particularly when it comes to deliverability. Even if you manage to avoid spam filters, nobody’s going to open an unsolicited email that’s been sent using unscrupulous means. It might even get reported as spam, which is going to start tanking your reputation with email address providers – and further reduce your deliverability.
What’s more, building mailing lists with web-scraping tools is actually illegal in a number of jurisdictions. In the US, for instance, the CAN-SPAM act means you can land yourself a hefty fine by doing this.
Bottom line: don’t web-scrape for addresses. As a matter of course, in fact, ensure that every email address on your list is someone who’s willingly signed up for it.

Use a Real Name in Your Sender Address
A surefire way of getting your emails sent to the spam folder (or blocked completely) is to use unrecognized, untrusted names, such as those of companies that are not particularly well known or regarded. Emails from generic accounts, like Gmail or Yahoo accounts, are also highly likely to end up undelivered (even to their own accounts!).
To obviate this, make sure that the sender address uses a real name. An authentic and trusted domain name helps even more; thus, “Sara@emailmarketing.com” is going to do better than either “sales@emailmarketing.com” or “Sara@hotmail.com”.
Remove Hard Bounces From Your Mailing List
Hard bounces are the result of sending emails to non-existent or dead email addresses. They’re also a guaranteed way of getting your organization blacklisted by ISPs in no time. Hard bounces are one of the foremost methods that ISPs use to determine if your emails get delivered or not; too many, and you’ll find your deliverability rate plummeting.
Ensuring the health of your mailing list is therefore an absolute priority, and it should be regularly pruned in order to ensure dead or non-existent email addresses are no longer an issue.
Have Your Domain Authenticated
As we touched upon before, an authenticated domain name is an important part of ensuring that your emails are not sent to the spam folder or outright rejected. But how do you have your domain authenticated?
There are two steps to this process:
- Provide your domain host with a Sender Policy Framework. An SPF is a record of DNS and IP addresses that are used by your organization, which can be published so that email providers can check to see that it’s really you sending the email. If you have an SPF in place, then you’re much less likely to have your email rejected.
- Obtain your Domain Keys Identified Mail. This email authentication protocol verifies that the content of your email wasn’t changed by a malicious third party in transit. Since it helps ensure the security of your email, ISPs are much more likely to trust emails originating with you.
Without these two things in place, your domain is vulnerable to email spoofing, whereby a third party uses your domain name to send malicious or spam emails. This hurts the reliability and reputation of your domain name, and will ultimately result in a lower deliverability rate.
Once your SPF and DKIM are in place, however, your domain will be much more trustworthy. In order to expedite the process of getting your SPF and DKIM, consider using an automated email marketing platform like HubSpot.
Use a Dedicated IP Address
If you’re routinely sending a lot of emails (and that amount keeps increasing) then you should seriously consider using a dedicated IP address to send them. Done properly, this means that you can use a private IP address that’s accessible to nobody else and that has a high level of trustworthiness in the eyes of ISPs.
However, you can’t simply grab a dedicated IP address and start sending tens of thousands of emails a week. It takes time for ISPs to ‘warm up’ to your new IP address, and you need to ensure that your organization is seen as reliable and trustworthy first. This means sending small batches at first, and striving for high open and click-through rates by sending your emails to brand-loyal people who are likely to open and click through on them.
Slowly but surely, you’ll be able to expand your use of the dedicated IP, and ultimately use it exclusively for all of your mass mailing needs.
Avoid Including Videos or Interactive Script Content
ISPs don’t like content-rich emails, such as those containing embedded videos, Flash, or dynamic content like those using JavaScript. Sending an email containing any of these things will almost certainly result in them hitting the spam folder before they hit the inbox – and even if they do make it through, the media you’ve included will likely be disabled. Repeated offenses will simply result in your being blacklisted.
Rather than embedding videos and other rich content directly, simply include an image of said media that contains a link to your website where people can watch the video/interact with the JavaScript content. That way you’re still exposing your subscribers to the content, while satisfying the requirements of most ISPs.
Use Double Opt-In Measures
A good deal of companies sign people up to their mailing lists simply by having them check a box – or, more commonly, having them not uncheck a pre-checked box. Because most people don’t bother reading things through carefully before hitting “accept”, it’s a quick and easy way of getting scores more subscribers onto your mailing list, right?
While it may seem this way, the fact is that tricking people into joining your mailing list (which is, at its heart, what the pre-checked box tactic amounts to) is simply going to result in a lot of spam reports and unsubscribes – both of which will ultimately damage your reputation with ISPs.
Avoid this by using a double-opt-in method of signing new subscribers up. This simply means that after someone has signed up for your mailing list, they’re sent a confirmation email that they must click through on before they’re signed up for your list. This way, you’re checking that people genuinely want to be on your mailing list, and keeping those spam complaints/unsubscribes down.
Make Sure Your Emails Don’t Look Like Spam
If the past twenty years have taught us anything, it’s how to immediately recognize and delete spam emails. Things like using block capitals, exclamation marks, and certain spam words/phrases (things like “earn $$$” or “make cash from home”) are a fast way to get emails marked as spam by the ISP before the recipient ever sees them – driving your email deliverability to zero.
By knowing what spam filters are looking for, you’ll be better equipped to avoid them. With that in mind, ensure that your emails don’t use the following:
High-Quality Links (or No Links At All)
If you’re using links in your emails (other than to your own website), you must ensure that those links are to reliable, high-quality URLs. It’s also crucial that you do not use shortened links like biturl or tinyurl ones), as these are frequently used by spammers and scammers to mask the nature of whatever they’re linking to.
If you want to avoid the spam folder, then, only use links to trusted websites (if you must use any at all).
All-Caps or Excessive Punctuation
Subject lines that are entirely in capital letters – or that use excessive question or exclamation marks – are a classic hallmark of spam emails, and though you may have legitimate reasons for using both (or either), the fact is that spam filters don’t discriminate with stuff like this. They’ll just send your email straight to the spam folder.
Words and Phrases Associated with Spam
It’s an unfortunate truth that a lot of phrases that are used quite innocuously in sales emails have become tainted by overuse, and are now inextricably linked with spam.
Such phrases include “extra cash”, “act now”, “free gift”, “potential earnings”, and many, many more. To be on the safe side, run your copy (and subject line) through a spam checker to make sure that your email is not going to throw up any red flags.
Inappropriate Image Use
If your email is one big image, with all the text and pictures part of that image, a spam filter is going to read that email as completely empty – and reject it accordingly. Never send an email that is simply an image.
Even when using images, make sure that they’re formatted properly. As noted, spam filters just see empty space where images should be, so make sure to write alt text for every image in your email.
Colored Fonts in Subject Lines
Colored fonts are a great way to have your email immediately stand out in subscribers’ inboxes, right? And the more eye-catching an email, the more likely it is to get opened, right?
That’s exactly what spammers think, too. And because of their propensity towards colored fonts, the reality is that spam filters will now automatically read emails with colored subject lines as spam. Stick to the standard color and find another way to make your email stand out.
Impersonal Content
Spammers are notable in that they are not known to their recipients; they simply send emails out wholesale without regard for how they acquired the email address and whether or not the recipient wants the email.
Avoid creating the impression that you are such a sender by personalizing your emails. Use your recipient’s name and include personal information so as to avoid the spam filters rejecting your emails.
Establish a Preference Center
The more in control your subscribers feel, the happier they are to be on your mailing list. By providing an email preference center, you can make sure that your subscribers are completely in the driver’s seat. They’ll be able to indicate how often they’re happy to receive emails, as well as what kind of emails they’d like to receive.
All of this ensures that they see the type of content they’d like to see; this means higher open and click-through rates and, for the purposes of deliverability, means that ISPs are ultimately going to see you as more trustworthy. Certain automated email marketing platforms like MailChimp can even take a lot of the busywork out of creating a preference center.
Perform Email Deliverability Tests
Once you’ve got all of these email deliverability best practices in place, it’s a good idea to ensure that everything is working as expected. In order to check that, you’ll need to carry out some email deliverability tests. These take several forms:
Content Checkers
This doesn’t refer to proofreading tools like Grammarly or Hemingway, but to content checkers that specifically check for spam. Such tools will check your content for some of the phrases we mentioned earlier, and will ensure that your email won’t be stopped at the door by ISPs.
Spam Filter Tests
One of the best ways of seeing if your email is going to be stopped by a spam filter is to subject it to actual spam filters. Open-source software like SpamAssassin can be used to assess your emails and ensure that they’re not going to be targeted by spam filters. Many platforms like MailerLite have SpamAssassin integrated, making checking your emails against spam filters even easier.
Link and Image Validation
Some email testing software is able to check the validity of any links or images you include in your mass mails. If there are red flags thrown up by the process – profanity within the links, alt texts or description, for instance, or broken paths/missing properties – then the tool will alert you, making it easy to fix and ensuring a higher deliverability rate.
Inbox Placement Testing
By testing whether or not your email actually lands in your subscribers’ inboxes (or if they end up elsewhere), you can head any troubles off at the pass and go back to the drawing board, ironing out any issues and ensuring email delivery optimization before you send the real thing out.
Be Sure Not to Fall Into Spam Traps
A “spam trap” is an email address that’s used by email community organizations and ISPs to catch spammers in the act. The only way to end up with a spam-trap email is by acquiring new email addresses in unscrupulous ways, such as purchasing email addresses or web-scraping them. Once you’ve emailed a spam trap, you’re on a list that’s extremely difficult to get off of.
How can you avoid picking up a spam-trap email? By keeping it clean. Use double opt-ins, make sure the only people on your list are people who want to be there, regularly prune your mailing list to make sure you don’t have any email addresses on there that shouldn’t be there, and never, ever purchase mailing lists.
As long as you play by the rules and only send solicited emails, you’ll never end up falling into a spam trap. And if you do, chances are you did something that earned you a place in that spam trap.
Never Include Attachments
Putting attachments like PDFs, Word documents and (especially) Excel spreadsheets will quickly get your email flagged as spam, and should be assiduously avoided. Excel spreadsheets in particular can be loaded up with harmful macros, and ISPs reject emails with such attachments (and others) as a matter of course.
To avoid this – but still ensure that the content is available to your subscribers – simply include a link to the file on your website. This ensures that your email will load faster, and that you won’t end up in the spam folder.
Some email marketing platforms, such as HubSpot, will automate the attachment link process for you, making it extremely quick and easy to avoid this issue.
Conclusion
By keeping it clean and ensuring that you don’t fall into the same traps that many known spammers do, you can ensure that your mailing list remains healthy and your company is reputable.
A lot of the tips and tricks that go into ensuring email delivery optimization really just boil down to operating ethically and with due diligence; as long as your company can do this (and why wouldn’t it?) then deliverability rates almost take care of themselves.
Of course, it doesn’t hurt to have a little help along the way. That’s why platforms like HubSpot, MailChimp, MailerLite and Sendinblue can be invaluable when it comes to improving email deliverability.